QCD corrections to the charged-Higgs-boson decay of a heavy quark

In recent papers QCD corrections to the decay $t\to H^{+}b$ were calculated by two groups with results that disagreed. Using dimensional regularization for both infrared and ultraviolet divergences, we confirm that the QCD corrections to the decay width $\Gamma (t\to H^{+}b)$ are equal to $\Gamma (t\to W^{+}b)$ in the limit of a large $t$-quark mass.